BACKGROUND: For a minimally invasive treatment approach to the anteromedial part of the anterior cranial fossa (ACF), a small incision and craniotomy of the posterolateral part of the ACF are preferable.
METHODS: We described the concept and technique of suprapterional keyhole approach (SPKA), which uses an exoscope and endoscope to treat ACF lesions.
CONCLUSIONS: The SPKA enables ACF observation from the lateral direction; the endoscope\'s extended viewing angles enable the observation of the anteromedial part of the ACF, including the bilateral olfactory groove. Facial skin and large scalp incisions are avoided, making this approach efficient for ACF lesions.

Solitary fibrous tumors are rare mesenchymal neoplasms that can develop in any part of the body, with those that settle intracranially being confused with meningiomas as a general rule. We present the case of a 57-year-old man referred to our hospital due to bifrontal headache, anosmia, and behavioral alterations of 6 months\' duration. Radiological studies revealed the existence of a large tumor mass with an extra-axial appearance and location in the anterior cranial fossa, initially compatible with a giant meningioma of the olfactory groove. Gross total resection of the mass was carried out. The pathological diagnosis was unexpected: a solitary fibrous tumor (WHO grade 1, 2021). Given the aggressive nature of these lesions, with a tendency to recurrence, malignant transformation and even metastasis, surgery with macroscopically complete resection intention should constitute the first therapeutic option. Close clinical-radiological follow-up after the procedure is justified.

BACKGROUND: Anterior cranial base meningiomas include those meningiomas originating from the tuberculum sellae, the planum sphenoidale, or the olfactory groove, with surgical excision being the main treatment modality for these tumors. Conventional microscopic and endoscope-assisted versions of the supraorbital keyhole approach via an eyebrow incision emerged into minimally invasive options that are frequently utilized nowadays for treating these tumors. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Notwithstanding, the fully endoscopic or endoscope-controlled version of the supraorbital keyhole approach is not routinely practiced by neurosurgeons, with few series published so far. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic supraorbital approach for anterior cranial base meningiomas.
METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic excision of anterior cranial base meningiomas via supraorbital approach were retrieved and analyzed. The pertinent literature was also reviewed.
RESULTS: The surgical technique of the fully endoscopic supraorbital approach for anterior cranial base meningiomas was formulated.
CONCLUSIONS: The fully endoscopic supraorbital approach for anterior cranial base meningiomas has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Introduction  Functional endoscopic sinus surgery and endoscopic skull base surgery are frequently performed surgeries today. Nasal septal deviation is a common finding and can affect the surgical area. Therefore, it is important to examine the effect of this deviation on other anatomical structures. Objectıve  The aim of the present study was to determine whether there is a relationship between the degree of nasal septal deviation and anterior skull base structures using computed tomography (CT). Methods  A total of 312 patients (aged 18 to 65 years old) whose paranasal sinus CT images were available were included in the study. Measurements were obtained on images retrieved from Picture Archiving and Communication System (PACS) and Horos image archive systems in the bone window in the coronal and axial plane. Results  The mean age of 312 patients was 33.00 years old (standard deviation [SD] 11.22 years). The presence of septal deviation was not associated with changes in olfactory fossa (OF) depths, Keros degrees, and the angle between the lateral lamella and the cribriform lamella. However, OF depths and Keros degrees on the deviated side of the septum were found to change at a significant level ( p  < 0.05). No significant association was observed between the degree of septal deviation and cribriform lamella-lateral lamella angle. Conclusion  The study showed significantly increased OF depth and Keros degree on the deviated side of the nasal septum. Performing CT scans before endoscopic sinus surgery and endoscopic skull base surgery is important to increase the chances of a successful surgical outcome and to reduce complications.

OBJECTIVE: Olfactory groove meningiomas (OGMs) often require surgical removal. The introduction of recent keyhole approaches raises the question of whether these tumors may be better treated through a smaller cranial opening. One such approach, the supraorbital keyhole craniotomy, has never been compared with more traditional open transcranial approaches with regard to outcome. In this study, the authors compared clinical, radiographic, and functional quality of life (QOL) outcomes between the keyhole supraorbital approach (SOA) and traditional transcranial approach (TTA) for OGMs. They sought to examine the potential advantages and disadvantages of open/TTA versus keyhole SOA for the resection of OGMs in a relatively case-matched series of patients.
METHODS: A retrospective, single-institution review of 57 patients undergoing a keyhole SOA or larger traditional transcranial (frontotemporal, pterional, or bifrontal) craniotomy for newly diagnosed OGMs between 2005 and 2023 was performed. Extent of resection, olfaction, length of stay (LOS), radiographic volumetric assessment of postoperative vasogenic and cytotoxic edema, and QOL (using the Anterior Skull Base Questionnaire) were assessed.
RESULTS: Thirty-two SOA and 25 TTA patients were included. The mean EOR was not significantly different by approach (TTA: 99.1% vs SOA: 98.4%, p = 0.91). Olfaction was preserved or improved at similar rates (TTA: 47% vs SOA: 43%, p = 0.99). The mean LOS was significantly shorter for SOA patients (4.1 ± 2.8 days) than for TTA patients (9.4 ± 11.2 days) (p = 0.002). The authors found an association between an increase in postoperative FLAIR cerebral edema and TTA (p = 0.031). QOL as assessed by the ASQB at last follow-up did not differ significantly between groups (p = 0.74).
CONCLUSIONS: The keyhole SOA was associated with a statistically significant decrease in LOS and less postoperative edema relative to traditional open approaches.

Objective  Anterior midline skull base meningiomas involving olfactory groove, planum sphenoidale, and tuberculum sellae were usually managed with bifrontal craniotomy until the dawn of advanced microsurgical techniques. With the emergence of microsurgical techniques, midline meningiomas could be tackled solely from a unilateral pterional approach. We present our experience with pterional approach in managing anterior skull base midline meningiomas, including the technical nuances and outcomes. Methods  Fifty-nine patients who underwent excision of anterior skull base midline meningiomas through a unilateral pterional craniotomy between 2015 and 2021 were retrospectively analyzed. The surgical technique and patient outcomes in the context of visual, behavioral, olfaction, and quality of life were evaluated during the follow-up. Results  A total of 59 consecutive patients were assessed over an average follow-up period of 26.6 months. Twenty-one (35.5%) patients had planum sphenoidale meningioma. Olfactory groove and tuberculum sellae meningioma groups consist of 19 (32%) patients each. Visual disturbance was the predominant symptom with almost 68% of patients presented with it. A total of 55 (93%) patients had complete excision of the tumor with 40 patients (68%) achieving Simpson grade II excision, and 11 (19%) patients had Simpson grade I excision. Among operated cases, 24 patients (40%) had postoperative edema among which 3 (5%) patients had irritability and 1 patient had diffuse edema requiring postoperative ventilation. Only 15 (24.6%) patients had contusion of the frontal lobe and were managed conservatively. Five patients (50%) with seizures had an association with contusion. Sixty-seven percent of patients had improvements in vision and 15% of patients had a stable vision. Only eight (13%) patients had postoperative focal deficits. Ten percent of patients had new-onset anosmia. The average Karnofsky score was improved. Only two patients had recurrence during follow-up. Conclusion  A unilateral pterional craniotomy is a versatile approach for the excision of anterior midline skull base meningioma, even for the larger lesions. The ability of this approach in the visualization of posterior neurovascular structures at the earlier stages of surgery while avoiding the opposite frontal lobe retraction and frontal sinus opening makes this approach more preferable over the other approaches.

Differential diagnosis of vision loss in a space-occupying lesion can be exhaustive. Olfactory groove meningioma (OGM) is a rare, benign, slow-growing tumour originating from the anterior cranial base. OGM is one of the differential diagnoses of intracranial tumours. We report a case of an OGM compressing the optic nerve and frontal lobe causing bilateral vision loss for six months. Multidisciplinary management by ophthalmologists, neurosurgeons, radiologists, and pathologists led to the diagnosis and tumour resection of OGM in the patient. Possible mechanisms of vision loss, imaging features, and treatment are discussed in this report.

The occurrence of an isolated schwannoma in the olfactory groove is extremely rare. We herein present 2 cases of schwannomas in the olfactory groove that were treated with endoscopic excision. In these 2 cases, the tumor originated in the cribriform plate and cerebrospinal fluid rhinorrhea occurred after tumor resection, which was repaired using tissue grafts.

There are several different approaches to large and giant olfactory-groove meningiomas (OGMs). Each approach has advantages and disadvantages. We present our series using a unilateral supraorbital keyhole approach avoiding the frontal sinus for the resection of large and giant OGMs without the use of fixed brain retractors or orbital rim removal.
All consecutive patients operated on for large (>3 cm in largest diameter) and giant (>5 cm) OGMs by the senior author from 2016 to 2021 were prospectively identified and retrospectively reviewed. Patients who were operated on using an endoscopic endonasal approach were excluded. No fixed retraction was used.
In total, 14 consecutive patients (11 with large, 3 with giant) were included. All patients were female, with an average age ± standard deviation of 59.7 ± 11.5 years. The median [interquartile range] preoperative Karnofsky Performance Status score was 80 [80-88]. The median preoperative tumor diameter and volume were 3.8 [3.2-4.2] cm and 22.2 [10.5-25.2] cm3, respectively. All patients underwent gross total resection. The median hospital stay was 2.7 [2-3] days, with all patients being discharged to home. No patients incurred any postoperative medical and/or surgical complications. Of the 9 patients who had subjective smell preoperatively, 5 stated they had subjective olfaction after surgery.
We demonstrate the utility of a unilateral supraorbital keyhole approach avoiding the frontal sinus for large and giant OGMs. The potential advantages of this approach are minimizing bilateral brain manipulation, avoiding the frontal sinus and potential mucoceles, and reducing the risk of cerebrospinal fluid leaks.

UNASSIGNED: The lateral supraorbital approach (LSO) provides an optimal access corridor for various skull bases lesions, including olfactory groove meningiomas (OGMs). The aim of this study is to describe the authors\' experience with the management of large and giant OGMs utilizing the LSO approach and describe the technical nuances of the procedure.
UNASSIGNED: A retrospective review of seven patients with large and giant OGMs managed with the LSO approach between 2013 and 2019 was performed. Radiographic and clinical data were recorded and analyzed.
UNASSIGNED: Seven patients with large and giant OGMs underwent surgical resection via the LSO approach. Six patients were female, with a median age of 56 years. Patients commonly presented with altered mentation, anosmia, and headaches. The average tumor volume was 120.6 ± 64.7 cm3 with five cases of vascular encasement. Simpson grade II resection was achieved in four patients while Simpson grade IV resection was achieved in three patients. The median length of stay was 2.0 days. The median preoperative Karnofsky Performance Scale (KPS) score was 70, improving to 100 at last postoperative follow-up visit. Two complications were encountered in the form of postoperative cerebrospinal fluid leak in one patient and a transient diplopia in another patient. Tumor recurrence/progression was identified in two patients during a median follow-up time of 65.5 months. Both cases have been managed with adjuvant radiosurgery.
UNASSIGNED: The LSO approach is a safe and effective minimally invasive transcranial corridor for the management of OGMs that should be part of the armamentarium of skull base neurosurgeons.